Amongst the various types of window hinge arrangements, one typical arrangement includes a hinge member having a track mountable to the window frame and a sash arm connectable to the window sash. When such a construction is used, a support arm interconnects the track and the sash arm, with the support arm being pivotally connected to both the sash arm and to the track. Conventionally, the sash arm is pivotally connected to a shoe which is supported and guided for movement longitudinally of the track. Typically, a casement window may have a window sash movably mounted within a frame by a pair of hinges mounted between the window frame and the top and bottom of the window sash. Alternative constructions use solely one hinge member mounted between the window frame and either the top or bottom of the window sash.
One of the main drawbacks associated with casement and awning window hinges is a condition known as sash-sag. Sash-sag is the condition that occurs in casement and awning windows when the sash portion of a window is out of square with the frame. This misalignment between the window sash and the frame can be caused by faulty installation of the window unit, settling of the building, warpage caused by weathering or other conditions. Indeed, when window hinges are installed, proper operation and sealing of the window when closed requires that the fixed track pivot be properly located relative to the window sash. Even if it is properly installed, over the life of the window, the proper location of the fixed track pivot may change due to slight shifting of the window, window frame, the building itself or any other condition resulting in a sag in the sash. When sash-sag occurs, the sash and the frame of the window are no longer square to one another when the latter is in the closed position or the edge of the sash which is opposite the hinges seems to sag in comparison to the frame of the window.
The problems with sash-sag are well known. Thus, a window with sash-sag will not seal properly and will not serve its purpose of preventing the ingress of moisture and dust particularly when driven by wind. As a result, the interior environment is not as well controlled and the window is not energy efficient. Furthermore, substantial damage can occur to the window itself and particularly, when the window frame is of wood. Thus, moisture can enter and cause structural damage both to the window frame and surrounding structures.
The prior art methods of installing window hinges in a precise manner and later correction of sash-sag have usually required that the hinge track be provided with slotted holes and slotted apertures and that the hinge mounting screws in the slotted apertures be removed to allow the shifting of the track. Repeated removal of such screws can, however, cause gradual loosening of the strength of the mounting. During the setting of the frame operation, the installer may either choose to securely tighten the screws before checking the alignment with the disadvantage that subsequent adjustment requires that the screw be loosened again, which further exacerbates the potential loss of strength in the mounting or, alternatively, the installer may choose to check the alignment before securely tightening the screws, causing potential slippage of the track when the window is re-opened to allow access to the screws for tightening, with the result that the track once finally tightened might still slightly be misaligned.
It is known in the art to have adjustment devices to overcome the above problems. However, normally the prior art adjustment devices are relatively labor intensive and complex.